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VOL. 39. CLEVELAND, MARCH 4, 1909. NEW YORK No. 9 Centrifugal Pump Fire Boats. The modern fire-boat has become a necessary adjunct to the fire depart- ments of sea, lake or river cities, and is viewed by underwriters as an im- portant factor in determining insur- ance rates. Not only is the fire boat a _ mneces- sity for the extinguishing of fires along a water front, or protecting shipping, but it is now rapidly coming into use as. an auxiliary water. .supply to 'the municipal pumping piants in cases of large or dangerous conflagrations. The pressure maintained and the vol- ume supplied by the ordinary water supply system of the average city is insufficient in extreme cases and most of the large cities are now installing the system of water mains drawing their supply directly from the water front. To illustrate the value of the mod- ern fire-boat and to demonstrate that the tendency is toward larger and more powerful boats, Plate 1 shows the street plan of one of our medium- sized marine cities with the auxiliary mains indicated thereon. Suitable con- nections are provided where these mains lead 'to the river. The absolute feasibility and practicability of this high-pressure main system has been demonstrated, and when these mains fin- ally extend some distance inland, as they some day will, there will be higher pressure and more capacity required of the pumps on the fire- boat. ; The city of New York has lately opened some high-pressure pumping stations on different points. in the water front for fire protection, con- *Paper read before Society of Naval Archi- tects and Marine Engineers. New York, Noy. 20, 1908, by Mr. W. I. Babcock in the ab- Sence of Mr. West. & BY CHARLES C. WEST, ESQ., MEMBER. sisting of multiple stage centrifugal pumps operated by. electric motors. A good fire-boat with its shore connec- tions accomplishes, of course, the same purpose. The commercial which almost causes advantage a business con- gestion near' a water front demands ample protection, and therefore the size and capacity of fire-boats have grown with the cities. Owing to the comparatively tempor- ary nature of American building con- struction, the fire-boat has developed in the United States more rapidly than in foreign countries, and today the boats of found over here. In the design of a fire-boat local conditions are of course of. impor- tance in determining such considera- tions as speed, ice-breaking and man- euvering qualities, etc, but in view of the fact that a fire-boat is merely a self-propelled pumping plant, interest centers in the pumps and the many fittings not common to other craft. For years there has been little differ- ence in the great number of fire-boats built in all parts of the country. In most cases identical pumping machin- ery was used, differing only in the number of units installed. These units consisted of double-cylinder, ver- tical, inverted reciprocating pumps, each unit having rated a capacity of about 3,000 gallons per minute. Plates 2 and 3 show typical boats equipped with these pumps. In prder to get a smooth nozzle stream and sufficient pressure and have the pumps contained in the limited space offered by an ordinary hull, it was necessary to run these pumps at an exceedingly high speed. As a con- sequence, however, the strains on the machine were enormous, in addition to largest capacity. are to: be- which was the ever-present danger of valve trouble. | The _ reciprocating : pump, however, has served its pur- pose creditably, but the demand which has come for higher pressures makes its future adoption questionable. Development of the Centrifugal Pump. The development ot the centrifugal pump of the multiple stage variety is comparatively recent, and the advent of the steam turbine has aided in its adoption, owing to the high speed at- tainable. In the boats equipped with turbines and two-stage centri- fugal pumps in use at the _ present time, there has been no difficulty in ob- taining higher pressures than are pos- sible in the reciprocating pump. This pressure can be easily increased by increasing the number of stages with no effect on the structure or working of the pump. Plates 4 and 5 show designs of cen- trifugal pump boats, the latter being one designed by W. I. Babcock for the eity of Chicago. The type of turbine used.so far in operating these centrifugal pumps has been the horizontal impulse type. While this type of turbine possesses the advantage of being more compact than the reaction turbine, it is also claimed by turbine builders that it can be started without being warmed up, a performance said to be dangerous in the reaction turbine owing to the liability of warping the spindle. In the operation of fire-boats of late years the latest practice has been to use hose lines less and discharge the streams either directly from the boat from stationary nozzles, or, as before . mentioned, into underground water mains. With the powerful streams now at the command of the firemen, it is of course necessary that the huge noz-